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To know how to grow old is the masterwork of wisdom, and one of the most difficult chapters in the great art of living. Henri Amiel
Old age is entirely new. There has never been anything like it before-at least to any substantial degree. It is the ultimate epidemic. There have been occasional old people before, but not like this. In 1900, there were 123,000 persons in America over 85 years of age. Now there are 3 million. By 2050, some estimates predict there will be as many as 50 million. That's 16 percent of the population, compared to 1 percent now. Talk about a "megatrend"! In that same year, all of my four children will be over the age of 85. I will be 120.
If I had been born in 1830 instead of 1930 I would have been dead for 30 years, but instead I am still running marathons.
How can this be? Let me begin by considering a machine-the perfect machine. Its cogs and pulleys are meshed to ultimate efficiency. Its struts and joints are sturdy. Its utility is manifest; its fuel is plentiful; its maintenance is negligible; its cost of production is minimal; its raw materials are abundant. It is friendly, versatile, and adaptable, and its operation is perpetual-or, failing that, its final disruption is abrupt.
Measured against such a design, the human body rates poorly. True, production costs are low, delightfully so; and maintenance and fuel costs are manageable. In its early years it is capable of wondrous efficiency. But a manufacturer would balk at the expense of a body's repair. It rusts out before its projected useful life is spent, and its final breakdown costs too much and takes far too long. The report of an industrial consultant would conclude that the human machine doesn't last as long as it is designed to last, and that its terminal operation is characterized by expensive decay and intolerable inefficiencies. The consultant would wonder whether these defects are secondary to blueprint errors (nature) or to environmental mishaps (nurture).
The Age Age
More than one historic epoch has been labeled a "watershed moment." Each was a cohesion of population dynamics and environmental challenge which provided a change in the course of human history. Each altered the mechanisms and direction of evolution. They are the monuments of punctuated equilibrium. Historians seem to take delight in identifying certain parts of our species' calendar by "age labels." We have had the Stone Age, the Bronze Age, several Ice Ages, the Agricultural Revolution (which Dr. Richard Leakey claims represents the single most significant event in human history), and the Industrial Revolution. With some pride and justification, the historians have already labeled our current epoch the Space Age. However, with equal propriety, appropriateness, and sense of history our time can be called the Age Age. This definition of our contemporary era derives its force from two elements: first the sheer number of old people alive today, and second, and more important, the fact that we have for the first time a soundly based idea of how long we are meant to live, and the forces which disrupt this logical extent.
In the past, death appeared randomly, as an unexpected event, like a dish breaking in the dishwasher. Until now, growing old was an accident, a survival based upon chance rather than design. Everything was foreshortened. As a child I regarded my 70 year old grandparents as extremely old-now, 70 years later, the seventies are increasingly acknowledged as part of middle age. For the aboriginal being-as well as for the animal-old age was the unlikely result of having survived myriad hostile encounters with unknown hazards and unexpected events. Daily existence was precarious. No one knew how many tomorrows there were to be or how to define a coherent life pattern. Such ignorance bred fear; and this accounts for much of what we see today as a starkly negative imagery concerning aging.
It is time for us to change. Present knowledge has expanded sufficiently for us to glimpse our entirety-to estimate the ultimate potential of the human life span.
What is the Human Life Span?
An animal may grow old in the wild, but not often. Accidents and predators keep the old members few. Evolutionary theory would predict that the onset of age and protracted weakness would not serve the survival of the species. History's great killers-famine, pestilence, lust, and war, the four horsemen of the Apocalypse-are largely controlled. New killers-arteriosclerosis, cancer, and automobile accidents-emerge. But if all external influences were eradicated, how long would it take for our machine to self-destruct? In the past, most people died young. Now most people have the chance to grow old. In I960, there were 3,000 centenarians counted in the United States. Now there are 71,000. There will be 114,000 in 2010, 241,000 in 2020, 1 million Americans over the age of 100 in the year 2050, and 1.8 million in 2080. Kenneth Manton, a scholar and demographer of aging at Duke University, calculated that 1 percent of male boys born in 1975 can expect to reach the age of 105, and 1 percent of female babies born that same year will live to 110.
My own clinical experience reflects this trend. I have cared for several dozen patients over 100. I have had the opportunity to care for one person who was 108 when he died. I have cared for thousands of persons in their nineties. Before her death at nearly 95, my mother still went to baseball games and traveled independently.
How Old is Old?
For how long is our machine designed to run? The Guinness Book of World Records observes, "... no single subject is more obscured by vanity, deceit, falsehood, and deliberate fraud than the extremes of human longevity. Extreme claims are generally made in behalf of the very aged rather than by them."
A few years ago our attention was drawn to three population groups, one in Hunza (a region in northern Pakistan), one in southern Russia, and one in Ecuador.
An article in National Geographic by Dr. Alex Leaf, of the Massachusetts General Hospital, told of these peoples-many of whom were said to be living healthy, active existences until age 130 and beyond. Shirlibaba Muslimov of the Russian republic of Azerbaijan was said to have died at the age of 168. Commissar Stalin, a Georgian, supported the claims. The state bureaucracy hastened to advertise this endorsement for the virtues of communist living. The story had a lovely, bucolic Shangri-La flavor to it. Unfortunately, it wasn't true. Careful examination of these groups has revealed that the longevity of these persons was due to exaggeration rather than to some particular invulnerability or salutary lifestyle. Zhores Medvedev, an expatriate Russian gerontologist, did much to debunk the legend by revealing the inaccuracy of the records and the incompatibility of the observed events with the reported ages. It was noteworthy that all of the "old" Russians were men who had likely taken their fathers names in order to avoid conscription.
In 1979, Richard Mazess and Sylvia Forman, of the University of Wisconsin, studied reports of extreme aging among the native population in Ecuador. The scientists worked meticulously to construct genealogical lineages and precise dates, but ultimately found no one over the age of 86.
The explanation: the Ecuadorians achieved heightened status by claiming to be very old.
One of the most celebrated oldsters of all time was Old Tom Parr of Shropshire, England. His headstone in Westminster Abbey gives his dates as 1482-1635 and notes that he lived in the reigns of ten kings. However, the attribution of Parr's age actually came from a confounding with another Tom Parr, two generations younger.
Social Security records in our own country indicate that Charlie Smith was born in Africa in 1842 and was still alive in 1980. More recent documents, however, revealed that this too was an overstatement. Mr. Smith was only 101, not 138.
The mythical Shangri-La remains undiscovered. The "supergerons" weren't.
Documentation of true age is a relatively new practice, even in civilized countries. For example, there were no written records in Russia before 1932. Most age records must be deduced from corollary events and likelihoods thereby constructed. On a recent trip to Borneo I sought out evidences of those of long life. A few centenarians were claimed, usually dating their age and activities from the time of the Japanese invasion in 1941. I was fascinated to learn, however, of a Dayak who recalls the eruption of Mt. Krakatoa, in 1883!
How Long Are We Actually Living?
Today, most of us live to approximately 78 years of age-slightly longer than the biblically predicted three score and ten. Meanwhile, scholars continue to search for proof of our upper limits. My Stanford Medical School colleagues James Fries and Lawrence Crapo published a fine, thoughtful book called Vitality and Aging, in which they muster evidence which indicates to them that our life expectancy is 85 years. This wouldn't give us much extra time to shoot for. More recent actuarial data seem to indicate that many of us are approaching or exceeding this projected end point. Concurrently, Dr. George Sacher has observed that there is a correlation between the life span of a number of animal species and their body and brain weights. Smaller animals with smaller brains have proportionately shorter lives than do larger animals with larger brains. Using this approach, he has calculated that mankind's maximum life span is approximately 90 years. In fact, both estimates are too low.
In an article from The Aging Society, Paul Siegel and Cynthia Taeuber (citing data from the Census Bureau) wrote: "If the average annual rates of decrease in age specific death rates recorded in the years since 1968 continue to prevail in the coming 65 years (to 2050), the average life expectation would approximate 100 in that year."
How Long Are We Meant to Live?
Dr. Robert Butler, first director of the National Institute on Aging and long recognized as a master in the field of gerontology, has said, "We haven't found any biologic reason not to live to 110.
"I'll go a bit further. It is my best estimate that our biogenetic maximum life span is 120 years-approximately 1 million hours. This means that at birth we have the capacity to live that long-presuming that nothing happens to us in the meantime. The lines of evidence that lead to this conclusion are several, and while no single one can constitute definitive proof, taken together they achieve a high level of probability. Such reasoning is termed the Principle of Invariance. If it rains for seven days straight, it is likely that it is the rainy season. One or another rainy day doesn't imply this; but when a whole week is wet, the conclusion is inescapable. Using this principle, I find five lines of evidence to support my thesis. These are: observational data, biostatistical maneuvers, the correlations between longevity and skeletal maturation, studies regarding the decline of vital organ function, and research into the longevity of cells in controlled environments.
The first reason to state that 120 years is our longest life span lies in the fact that some of us are living that long. The Guinness Book of Records indicates that Madame Calment set the pace. Her dates were February 21, 1875-August 4, 1997.
Their earlier edition listed Shigechiyo Isumi of Asan, Japan, as the oldest person, having lived from June 29, 1865, until February 21, 1986 (120 years, 237 days). I have corresponded with his physician, Dr. Yoshinobu Moriya, who reported that Mr. Isumi was healthy until the end of December 1985. "He was willing to shake hands with many visitors, especially with young ladies. Many thought that this custom was a moment [sic] for his longevity," the doctor said. Mr. Isumi also moderately drank a local sugar cane wine. His death was listed as being due to pneumonia, and heart and kidney insufficiency.
After these records a 116 year old female from Ecuador and a 114 year old man from Puerto Rico are listed as the world's oldest persons as of April 2006.
Thousands of people are crowding upward; and as worldwide birth records improve, others of long life will be identified. It must be emphasized that these long lives are being achieved despite the continued presence of major health hazards such as environmental pollution, an excess of fat intake, and sedentary life styles. The Japanese have the world's longest life expectancy despite a very high incidence of stroke; and this brings us to a second line of reasoning. In a statistical projection, the California State Department of Health constructed a scenario in which it was presumed that one or another of our major killers had been eliminated. The results were quite revealing. For example, when such a hypothetical prevention of arteriosclerosis is applied, the average female achieves an expected life of 100 years. The figure of 120 is consistent with this projection.
Kenneth Manton, of Duke University has constructed other such projections. By analyzing extensive U.S. Census data he calculated that in 1982 the "life endurance" of American white females was 114 years and still rising.
In The Medusa and the Snail, Dr. Lewis Thomas wrote, "Mankind will someday be able to think his way around the finite list of major diseases that now close off life prematurely or cause prolonged incapacitation and pain. In short, we will someday be a disease free species." Having risen to such an exalted and extended state of grace, Thomas goes on to ask, "Then what? How can you finish life honorably and die honestly without a disease?"
If our research scientists can provide us with the master protocol to eliminate disease-the ultimate vaccine-it seems to me that 120 years is the logical end point. This presumes, of course, the lack of self-destruction and of accidents-but most of those are preventable as well.
Longevity and Skeletal Maturation
George Buffon, a noted French biologist who predated Charles Darwin, observed a close relationship between the time of skeletal maturity and life span across a broad range of animal species. The intense relationship between growth and life will be elaborated upon later; but in general terms; large animals live longer than small ones. Specifically, when Buffon made his study, he recognized that animals tended to live six times the period needed to complete their growth. When one notes that skeletal maturity is reached in humans at approximately 20 years, the maximum projected life span of 120 years is affirmed.
More recently, Richard Cutler, of the Gerontology Research Center of the National Institutes of Health in Baltimore, has calculated the mean lifetime potential (MLP) of a number of animal species. He finds that longevity is related to the rate of development, length of reproductive period, maximum caloric consumption, and brain size. The MLP varies 50fold over the animal range, from 3 years in the house mouse to 20 years for the dog, 70 years for the elephant, and 100 years for the whale. Cutler calculates that with this refinement he can estimate mankind's MLP at 110 years.
Importantly, the rate of aging in different species is also found to correlate with the MLP. For example, the loss of immune competence (or reactivity) in man and the mouse is inversely proportional to the MLP. Our capacity to reject foreign skin grafts also seems related to how long we can live. The older we become, the less able are our tissues to generate antibodies to offending agents. Physical vigor, resistance to disease, and numerous other functional markers are similarly related to MLP and (also according to Cutler) can be used to estimate man's MLP as being 110 years.
How long an animal lives also correlates with the observed decline in vital organ function, which brings us to the fourth line of reasoning.
Excerpted from We Live Too Short and Die Too Long by WALTER M. BORTZ II Copyright © 2007 by Walter M. Bortz II, M.D.. Excerpted by permission.
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